To replace the femoral condylar slide surfaces of the knee joint, slide surface prostheses are known which are designed relatively thin and thus require only minimal resection of the cartilage and bone material, and in some cases permit partial or complete preservation of the hard cortical bone. The prosthetic slide surfaces which are assigned to the two condyles are generally connected by way of a scutiform part which protrudes upwards on the anterior aspect and forms a slide surface for the patella. Such a connection of the condylar slide surfaces ensures that they are positioned correctly matching each other. In many cases, it is not necessary to replace the patellar slide surface. A simpler connection of the two condylar slide surfaces would then be sufficient. However, experience has shown that a simpler connection is often unable to cope with the loads arising during use and so breaks. Instead of this, it is possible to employ unconnected condylar slide surfaces, but these have the disadvantage that their correct mutual positioning is not really possible without manual intervention.
An instrument is known (cf. brochure "Schalen-Kniegelenkprothesensystem SKI" from the company Interplanta GmbH, Hamburg) which is used for inserting mutually positioned tibial plateaus and which has two mutually parallel pins which can each be introduced into a bore in one of the plateaus, and two spikes which run transverse to these pins and engage in each case in a transverse bore. Such a solution is not feasible in the case of condylar slide surface prostheses, mainly because the position of the slide surface does not permit provision of the said bores.